Chance and time are intimately linked in our universe. Every day, chance occurrences take place that present us with new opportunities, challenges and perils. To make the best of them requires a knowledge of how to make decisions in sequence. Nowhere is this more true than in the realm of love. A single person will meet a large but limited number of available prospects over a lifetime, and a key question is: How do you know when you've met the right person for you, the person you would like to marry? (The assumption here is that once you've severed a relationship with someone, he or she is gone.)

A mathematical theorem has been developed that gives us the best sampling and stopping for this situation:

You will maximize your probability of finding the best spouse if you date about thirty-seven percent of the available candidates in your life, and then choose to stay with the next candidate who is better than all the previous ones.

This is, indeed, a very strange-sounding rule. But mathematicians have proved it works better than any other. The number thirty-seven percent is an approximation of the exact number 1/e, where e is the base for natural algorithms, or 2.71828. Suppose over a lifetime you expect to meet one hundred candidates. If you marry the first one, the chance that you have indeed found the best of all one hundred candidates is only 1/100. Likewise, if you wait to meet all one-hundred candidates, you will have rejected the ninety-nine who came before, and the possibility that the last person you meet is also the best is again only 1/100. The best strategies allow you to sample for a while, in order to learn about the various candidates; and of all such strategies, the best has you sampling thirty-seven percent of the total and then choosing the first candidate thereafter who beats all the ones who came before. Of course, there is a chance you will never find one who is better than all thirty-seven percent you've already seen. But nothing is certain in love.